High brightness directional direct emitter with photonic filter of angular momentum

ABSTRACT

A nano-structure layer is disclosed. The nano-structure layer includes a plurality of nano-photonic structures that are configured in a first configuration such that light incident upon the nano-structured layer below a cutoff angle passes through the nano-structured layer and light incident upon the nano-structured layer above the cutoff angle is reflected back in direction of the incidence.

BACKGROUND

A typical light-emitting diode (LED) emitter generally produces aLambertian radiation emission distribution pattern such that theradiation, when observed from an ideal diffuse radiator, is directlyproportional to the cosine of the angle between the direction of theincident light and the surface normal. Secondary optics can be used toshape radiation so that it is more directional. Such optics can be bulkyand may limit the benefits of the small form factor of the LED. Also,often times, the secondary optics can be lossy or simply not optimizedfor efficiency and, hence may end up absorbing a large portion of theemitted radiation.

SUMMARY

A nano-structure layer is disclosed. The nano-structure layer includes aplurality of nano-structure material that are configured in a firstconfiguration such that light incident upon the nano-structured layerbelow a cutoff angle, with respect to normal, passes through thenano-structured layer and light incident upon the nano-structured layerabove the cutoff angle is reflected back in direction of the incidence.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding can be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a diagram of light emitting device with a nano-structurelayer;

FIG. 1B is a graph showing a Lambertian radiation emission versus adesired radiation emission distribution pattern;

FIG. 1C is graph showing reflectance as a function of angle;

FIG. 1D is a diagram showing light beams at different angles;

FIG. 1E is two graphs showing transmission based on angular frequency;

FIG. 1F is a chart showing relative flux gains over cone angles based oncutoff angles;

FIG. 1G is a chart showing transmission as a function of angle;

FIG. 1H shows example nano-antennae;

FIG. 1I is a graph showing transmission based on angle of incidence;

FIG. 1J is a transmission angular map for scattering;

FIG. 1K is a reflectance angular map;

FIG. 1L is a multi nano-structure material array;

FIG. 1M is a flow diagram for light emission through a nano-structurelayer;

FIG. 2A is a diagram showing an Light Emitting Diode (LED) device;

FIG. 2B is a diagram showing multiple LED devices; and

FIG. 3 is a diagram of an example application system.

DETAILED DESCRIPTION

Examples of different light illumination systems and/or light emittingdiode implementations will be described more fully hereinafter withreference to the accompanying drawings. These examples are not mutuallyexclusive, and features found in one example may be combined withfeatures found in one or more other examples to achieve additionalimplementations. Accordingly, it will be understood that the examplesshown in the accompanying drawings are provided for illustrativepurposes only and they are not intended to limit the disclosure in anyway. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms may be used todistinguish one element from another. For example, a first element maybe termed a second element and a second element may be termed a firstelement without departing from the scope of the present invention. Asused herein, the term “and/or” may include any and all combinations ofone or more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it may be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there may be no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element and/or connected or coupled tothe other element via one or more intervening elements. In contrast,when an element is referred to as being “directly connected” or“directly coupled” to another element, there are no intervening elementspresent between the element and the other element. It will be understoodthat these terms are intended to encompass different orientations of theelement in addition to any orientation depicted in the figures.

Relative terms such as “below,” “above,” “upper,”, “lower,” “horizontal”or “vertical” may be used herein to describe a relationship of oneelement, layer, or region to another element, layer, or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

Semiconductor light emitting devices or optical power emitting devices,such as devices that emit ultraviolet (UV) or infrared (IR) opticalpower, are among the most efficient light sources currently available(hereinafter “LEDs”). These LEDs, may include light emitting diodes,resonant cavity light emitting diodes, vertical cavity laser diodes,edge emitting lasers, or the like. Due to their compact size and lowerpower requirements, for example, LEDs may be attractive candidates formany different applications. For example, they may be used as lightsources (e.g., flash lights and camera flashes) for hand-heldbattery-powered devices, such as cameras and cell phones. They may alsobe used, for example, for automotive lighting, heads up display (HUD)lighting, horticultural lighting, street lighting, torch for video,general illumination (e.g., home, shop, office and studio lighting,theater/stage lighting and architectural lighting), augmented reality(AR) lighting, virtual reality (VR) lighting, as back lights fordisplays, and IR spectroscopy. A single LED may provide light that isless bright than an incandescent light source, and, therefore,multi-junction devices or arrays of LEDs (such as monolithic LED arrays,micro LED arrays, etc.) may be used for applications where morebrightness is desired or required.

LEDs that increase radiation within a narrow angular range vianano-structured layers are disclosed. The disclosed implementations mayallow control over beam direction for normal or side emission. Thedisclosed implementations may be used for any direct emitterapplications including, but not limited to infrared (IR) applications,single wavelength applications, or the like.

A nano-structure layer may include nano-structure material such asmeta-surfaces, plasmonic nanostructures, meta-molecules, photoniccrystals, among others. As used herein, photonic crystals andmeta-surfaces may be periodic arrangements of meta-atoms and/ornano-antennae. A meta-atom nano-structure layer may include an array ofmeta-atoms. A nano-antenna nano-structure layer may include one or morenano-antennae. Nano-structured layers, as disclosed herein, mayincorporate the design of LED devices with nano scale optical antennasplaced on an LED surface (e.g., a sapphire substrate).

The design and optimization of controlling beam direction of LEDs isdisclosed. By way of example and in order to provide concretedescription, a flip chip of chip scale package (CSP) LED with a sapphiresubstrate is described, although the principles and teaching herein maybe applied to any applicable LED design. A sapphire based CSP emitterwith a smooth light escape surface (LES) may allow deposition of anano-structured layer such that light emitted by an LED is incident uponthe nano-structured layer via the sapphire substrate.

A nano-structured layer may transmit radiation within a limited angularrange. The limited angular range may be one that renders apre-determined angular radiation pattern in the far-field. As anexample, an LED configured to increase brightness at normal (e.g., at 0degrees, or, straight) to a light emitting surface, may be manufacturedusing a nano-structured layer as disclosed herein. To increasebrightness at normal, a nano-structured layer may create an angularfilter that transmits lights at angles lower than an angular cut-offangle and reflects radiation above the angular cut-off angle, as furtherdisclosed herein. Light incident at an angle lower than the angularcut-off angle may be transmitted through the nano-structured layer andmay be re-radiated into preferred cone angles (e.g., +/−5 deg, +/−45deg, and +/−60 deg, etc.) as further disclosed herein.

The nano-structured layers disclosed herein may include nano-antennaeplaced in a pre-determined arrangement to re-radiate emission intopreferential angular directions. The preferential angular directionbased radiation may be a deviation from a Lambertian radiation emissionsuch that it may be shaped by a nano-structured layer to re-radiatelight into preferred cone angles. The nano-structured layers disclosedherein may utilize a partial band-gap to restrict the angular momentumrange of radiation. The partial band-gap may be determined based on aconfiguration of the nano-structured layer(s) such that radiation isonly allowed within a particular range of angles, for example, center tonormal or near grazing (highly oblique radiation).

FIG. 1 illustrates an LED device 100 including a nano-structured layer110 on top of an LED device that includes an epitaxial grownsemiconductor layers 130 and substrate 120. The epitaxial grownsemiconductor layers 130 may include a first contact 131 and a secondcontact 132 separated by a gap 133 which may be an airgap or may befilled with dielectric material. A p-type layer 134 may be proximate toan active layer 135 and an n-type layer 136. The active layer 135 may beconfigured to emit light distal from the contacts 131 and 132 such thatlight beams emitted from the active layer 135 are generally emittedtowards the substrate 120. The LED device 100 is presented in asimplified form for ease of understanding of the invention, knowing thatone possessing an ordinary skill in the pertinent arts would understandthe other elements included within an LED.

The epitaxial grown semiconductor layers 130 may be formed from anyapplicable material configured to emit photons when excited includingsapphire, SiC, GaN, Silicone and may more specifically be formed from aIII-V semiconductors including, but not limited to, AlN, AlP, AlAs,AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductorsincluding, but not limited to, ZnS, ZnSe, CdSe, CdTe, group IVsemiconductors including, but not limited to Ge, Si, SiC, and mixturesor alloys thereof. These example materials may have indices ofrefraction ranging from about 2.4 to about 4.1 at the typical emissionwavelengths of LEDs in which they are present.

For example, Aluminum nitride (AlN) may be used and is a wide band gap(6.01-6.05 eV at room temperature) material. AlN may have refractiveindices of about 1.9-2.2 (e.g., 2.165 at 632.8 nm). III-Nitridesemiconductors, such as GaN, may have refractive indices of about 2.4 at500 nm, and III-Phosphide semiconductors, such as InGaP, may haverefractive indices of about 3.7 at 600 nm. An example gallium nitride(GaN) layer may take the form of a layer of pGaN. As would be understoodby those possessing an ordinary skill the pertinent arts, GaN is abinary III/V direct bandgap semiconductor commonly used inlight-emitting diodes. GaN may have a crystal structure with a wide bandgap of 3.4 eV that makes the material ideal for applications inoptoelectronics, high-power and high-frequency devices. GaN can be dopedwith silicon (Si) or with oxygen to create an n-type GaN and withmagnesium (Mg) to create a p-type GaN as is used in the present example.The active layer 135 is the region where light is emitted aselectroluminescence occurs. Contacts 131 and/or 132 coupled to the LEDdevice 100 may be formed from a solder, such as AuSn, AuGa, AuSi or SACsolders.

As shown in FIG. 1A, substrate 120 may be located between thesemiconductor layers 130 and the nano-structured layer 110. Thesubstrate may be a CSP emitter with a smooth LES that enables depositionof the nano-structured layer 110. The substrate 120 may comprisesapphire, which is an aluminum oxide (Al2O3) also known as corundum, andcan exhibit properties including being very hard, strong, easy tomachine flat, a good electrical insulator, and an excellent thermalconductor. Sapphire is generally transparent when produced syntheticallywith the blue color in naturally occurring sapphires (and the red inrubies, which are another form of corundum) coming from impurities inthe crystal lattice. In other LEDs, the sapphire may be replaced withgallium nitride (GaN). The semiconductor layers 130 may be in the regionwhere light is emitted as electroluminescence occurs.

As shown in FIG. 1A, the sidewalls of the substrate 120 may be coveredby sidewall material 140. The sidewall material 140 may also cover oneor more layers of the semiconductor layers 130 such that either the samesidewall material 140 covers the substrate 120 and the semiconductorlayers 130 or a different material may cover the sidewalls of thesubstrate 120 than the semiconductor layers 130. The sidewall material140 may be any applicable reflecting or scattering material. Accordingto an embodiment, the sidewall material 140 may be a distributed Braggreflector (DBR).

As disclosed herein, to emit light at a pre-determined angularradiation, such as to increase brightness at normal, a nano-structuredlayer may create an angular filter that transmits lights at angles lowerthan an angular cut-off angle, with respect to normal, and reflectsradiation above the angular cut-off angle. Reflected radiation mayreflect back into the substrate 120 such that beams of radiated lightwithin the radiation are incident upon the sidewall material 140 and/ora back reflector 125 located below the active layer 135 and distal fromthe surface of the substrate 120 that faces the nano-structured layer110. The back reflector 125 may be a plasmonic layer including planarmetal mirrors, a distributed Bragg reflector (DBR) and/or other knownLED reflectors. The back reflector is designed to reflect the lightbeams that are reflected back into the substrate 120. The back reflector125 may reflect light beams before or after the light beams bounce offsidewall material 140 or may reflect light beams directly reflected bythe nano-structured layer 110.

The nano-structured layer 110 may include photonic materialsincorporated into photonic crystals and/or meta-surfaces which mayinclude meta-atoms and/or nano-antennae such that the largest dimensionfor a meta-atom or nano-antennae is less than 1000 nm. The nano-antennaecan be implemented as an array of nanoparticles located in thenano-structure layer, as further disclosed herein. The nano-antennas maybe arranged in either periodic or a-periodic patterns. In analogy withchemical molecules composed of atoms, a meta-surface is composed ofmeta-atoms with the meta-atoms combined together and interacting to givethe meta-surface unique optical properties. The size of individualmeta-surfaces may be sub-wavelength or may be formed at the same orderof wavelength of use.

The nano-structured layer 110 can also include nano-antennae that aredistributed throughout a host dielectric medium. The sizes of thenano-antennae may be a sub-wavelength of order of wavelength.

The nano-structured layer 110 may be designed with a configuration sothat its optical properties have a resonance or controllable propertiesat one or more wavelengths such that the configuration causesre-radiation of emitted light into a preferential angular direction(e.g., a desired cone angle of +/−5 deg, +/−45 deg and +/−60 deg, etc.).As a result, the nano-structured layer 110 behaves as an optical antennaand may radiate the light incident upon the nano-structure layer throughinto free space such that the light satisfies certain emissionconditions. This may be achieved by tuning the structure and chemicalcomposition of the nano-structure layer 110 so as to simultaneouslyexcite electric and magnetic dipoles, quadrupoles and higher ordermultipoles within the nano-structure layer 110. The simultaneousexcitation of the dipoles and higher order multipoles may tailor theemission properties of the nano-structure layer 110 to steer angularradiation such that light emitted by the LED device 100 is boostedwithin a given restricted angular range.

Tailoring of the configuration of the photonic crystals and/ormeta-surfaces in the nano-structure layer 110 enables transmission ofradiation incident upon the substrate within a limited angular range.Control of the angular emission patter (or directivity) may beaccomplished by either one or both of re-radiating emission into apreferred angular direction (e.g., via beam bending) or by restrictingthe angular momentum range of radiation (e.g., filtering incident lightbeams based on their angle of incident).

A nano-structure layer 110 may include nano-antennae arranged in anarray. The nano-antennae may be configured such that they re-radiateemission into preferential angular directions. A partial band-gap may beengineered to restrict the angular momentum range of radiation such thatradiation is only allowed within a particular range, for example,centered at or about normal. FIG. 1B shows an angular range centered at0 in the X direction and transmission in the Y direction. As shown inFIG. 1B, an example Lambertian radiation emission distribution pattern122 has a lower but wider transmission range when compared to a desiredradiation emission distribution pattern 121, provided in accordance withthe subject matter disclosed herein with the use of a nano-structuredlayer. As shown, the desired radiation emission distribution pattern 121shows radiation within a narrow angular range with a higher transmissionvalue within the narrower angular range.

FIG. 1C shows a graph with a Y axis of reflectivity and an X axis of anangle of incidence of light 151 incident upon a nano-structured layer110 of FIG. 1A. As shown, light incident upon the nano-structure layer110 at angles closer to normal (e.g., closer to 0 degrees) have areflectivity of near zero such that all light incident at such anglespasses through the nano-structure layer 110 without any or a minimalamount of light being reflected back into the substrate 120. As shown inFIG. 1C, the amount of reflectance may increase as the angle ofincidence increases such that the Θ_(C) 159 represents a cut-off anglewhere all light at or past the cut-off angle, with respect to normal, isreflected back into a substrate (e.g., substrate 120). At angle Θ_(TH),half of light incident upon the nano-structure layer 110 may bereflected, at 154, less than half the light may be reflected, and at156, more than half the light is reflected.

An example visual representation of this phenomenon is shown in FIG. 1Dby light beams 111 and 112. Light beams 111 and 112 may traverse thesubstrate 120 to the nano-structure layer 110. Light beams 111 with anangle of incidence below a cut off angle (i.e., closer to normal)traverse through the and out of the nano-structure layer 110 and lightbeams 112 with an angle of incident higher than a cut off angle (i.e.,further away from normal) are reflected back into the substrate 120. Asdisclosed herein, light beams reflected back into the substrate 120 mayexperience one or more bounces within the substrate and/or on a backreflector such that they may be incident upon the nano-structure layer110 a second time after being reflected into the substrate 120 by thenano-structure layer 110. A light beam that is reflected into thesubstrate by the nano-structure layer 110 at a first time may experienceone or more bounces within the substrate (e.g., at the sidewallmaterial, back reflector, etc.) and may be incident upon thenano-structure layer 110 at a second time after the first time. Theangle of incidence of the light beam, at the second time, may be lowerthan the cut off angle, with respect to normal, and accordingly, thelight beam may pass through the nano-structure layer 110.

FIG. 1M shows an example process 1400 of a beam transmission throughsubstrate 120 and nano-structure layer 110. At step 1410, a first lightbeam may be incident upon the nano-structure layer 110 after traversingthrough substrate 120. The first light beam may be incident at an angleabove the nano-structure layer 110's cutoff angle. At step 1420, thefirst light beam may be reflected back into the substrate 120 based onthe interaction with the nano-structure layer 110 at an angle above thecutoff angle, with respect to normal. At step 1430, a second light beammaybe incident upon the nano-structure layer 110 through the substrate120. The second light beam may be incident at an angle below thenano-structure layer 110's cutoff angle, with respect to normal. At step1440, the second light beam may be emitted through the nano-structurelayer 110 based on its interaction with the nano-structure layer 110 atan angle below the cutoff angle, with respect to normal. According to anembodiment, as discussed herein, the first light beam may bounce off oneor more inside surfaces of the substrate, sidewall material and/or backreflector and may be incident upon the nano-structure layer 110 at anangle below the cutoff angle. The first light beam may then be emittedthrough the nano-structure layer 110 based on the angle of incidentbelow the cutoff angle.

FIG. 1E shows charts 165 and 160 corresponding to the behavior of lightwhen incident upon the nano-structure layer 110. In chart 160, Wrepresents the angular frequency and K represents the in plane angularmoment. Light line 161 of chart 160 is determined based on theconfiguration of nano-structure layer 110 and represents the boundarybetween light that can pass through the nano-structure layer 110 andlight that does not pass through nano-structure layer 110. Further,limiting light below a given angular frequency W allows an LED toachieve the desired radiation emission distribution pattern 121 of FIG.1B. As shown in chart 165, the transmission output of light incidentupon nano-structure layer 110 is unity below Θ_(TH) and drops to zeroafter Θ_(TH) as a result of reaching the corresponding angular cutoffKth shown in FIG. 160. Accordingly, light emitted at K>Kth will passthrough the nano-structure layer 110.

FIG. 1F shows a relative gain in flux, by percentage, represented viathe Y axis, for various cone angles (5, 45, and 60 degrees) as well asfull width at half maximum (FWHM) reduction. As shown, in this example,cutoff 1 represents a cutoff angle of 10 degrees and cutoff 2 representsa cut off angle of 20 degrees. The experimental results shown in FIG. 1Fare obtained by using a 1 mm²CSP Gen 4 die with an AlN epi with sidewallmaterial. As shown, the relative flux gain for a nano-structure layer110 configured to emit a 5 degree cone angle was 214% for the 10 degreecutoff 171 and 45% for the 20 degree cutoff 172. The relative flux gainfor a nano-structure layer 110 configured to emit a 45 degree cone anglewas −12% for the 10 degree cutoff 173 and 27% for the 20 degree cutoff174. The relative flux gain for a nano-structure layer 110 configured toemit a 60 degree cone angle was −34% for the 10 degree cutoff 175 and−4% for the 20 degree cutoff 176. As shown, light emitted at a widercone angle but with narrow cut off experiences lower gain in flux. Asalso shown in FIG. 1F, the FWHM experienced at cutoff 1 177 is 62% andat cutoff 2 178 is 34%.

FIG. 1G shows transmission properties based on angle for thenano-structure layer 110 considered for simulation of the resultsprovided in FIG. 1F. As shown, 182 represents the 10 degree cutoffconfiguration of the nano-structure layer 110 and 184 represents the 20degree cutoff configuration of the nano-structure layer 110. Asrepresent by the 10 degree cutoff of 182, the transmission is at unityuntil approximately 10 degrees when the transmission amountsignificantly drops as a gradient to less than 10% of its peak value by20 degrees and drops to 0% of its peak value by 35 degrees. Similarly,as represented by the 20 degree cutoff of 184, the transmission is atunity until approximately 20 degrees when the transmission amountsignificantly drops as a gradient to less than 10% of its peak value by30 degrees and drops to 0% of its peak value by 35 degrees.

Photonic crystals and/or meta-surfaces in the nano-structure layer 110may be configured with a spatial gradient of phase. FIG. 1H illustratesvarious cross-sections of some different possible nano-antennae. Thenano-antenna may be formed from nano-cylinders 191, nano-cones 192, ornano-cone 193 and 195 with vertical or coaxial dimmers, arranged ineither hexagonal or rectangular lattice. The lattice period may besub-wavelength or larger than wavelength. The nano-antennae may beHuygen's meta-atoms or support waveguide modes. A Huygen'snano-structure layer with spatial variation of radius can also be usedto achieve the desired narrowing of the beam. Each photonic crystal ormeta-surface may present a certain amount of beam bending propertiessuch that incident beams can be shaped to the required angulardistribution. In the cases of the nano-cylinder vertical dimer 194 innano-cone 193 and coaxial dimer 196 in nano-cone 195, interfering modeswithin the meta-atom or nano-antenna provide additional control of thelight emitted through nano-structure layer 110, using structuralparameters. For example, the nano-antennae may be configured in anarrangement that establishes a given cutoff angle such that lightincident below the cutoff angle passes through the nano-antennae, andthus the nano-structure layer, and light incident above the cutoff angledoes not pass or is reflected back. Alternatively or in addition, thenano-antennae may be configured in an arrangement that results in agiven cone angle (e.g., +/−5 deg, +/−45 deg, and +/−60 deg, etc.) baseddistribution. The cutoff angle and the cone angle based distribution maydetermine the overall flux gain experienced by light emitted though thenano-structure layer 110.

Nano-antennae may be formed or arrayed as single nano-structure materialsuch that the same nano-antenna is repeated numerous times to form anano-structured layer. Alternatively or in addition, nano-antennae maybe formed or arrayed as multi nano-structure materials such that anarray of nano-antennae is repeated numerous times to form anano-structured layer. FIG. 1L illustrates an example multinano-structure material 1300. As shown, the multi nano-structurematerial 1300 includes nano-cylinders 1301 and 1302 such that thedifferent nano-cylinders 1301 and 1302 have one or more differentproperties when compared to each other. As a visual example, as shown inFIG. 1L, nano-cylinder 1301 is smaller in volume than the nano-cylinder1302. This multi nano-structure material may be arrayed such that anano-structure layer 110 includes multiple iterations of multinano-structure material 1300. Each small multi nano-structure material1300 of a nano-structure layer 110 may provide beam bending to the lightincident on nano-structure layer 110. By suitably placing a multitude ofdifferent nano-cylinders 1301, with different beam bending properties,within a multi nano-structure material 1300 within nano-structure layer110, light incident upon nano-structure layer 110 may be shaped to apredetermined or preferred angular distribution. The design andplacement within nano-structure layer 110 may selected by an optimizerto obtain the best possible flux from the LED device 100 of FIG. 1A. Thedesign of photonic crystals and/or meta-surfaces may be dictated by therequired angular distribution and the placement of the same can bedetermined based on an optimizer to obtain the optimal transmission overthe required angular distribution.

As disclosed herein, as the nano-structure layer 110 functions as anoptical antenna, the directivity of the emitted light may be tuned bytuning the configuration of the photonic crystals and/or meta-surfacesin the nano-structure layer 110. The photonic crystals and/ormeta-surfaces may be designed to provide collimated or un-collimatedlight emission from the LED at multiple wavelengths, beam-forming oflight emitted for different wavelengths, or the like. To clarify, theshape of a light beam emitted from the nano-structure layer 110 isdetermined by the interference of the beam scattered by the individualphotonic crystals and/or meta-atoms in the nano-structure layer 110 andfrom further interaction with neighboring nano photonic crystals and/ormeta-surfaces in the nano-structure layer 110.

The simultaneous excitation of electric and magnetic dipoles in thenano-structure layer 110 may be sufficient to suppress back-scatteringof light back into LED die and, thus yielding a large forward scatter.Such a nano-structure layer 110 may be built using purely dielectricnanoparticles, without using metals, thereby reducing absorption losses.

Photonic crystals and/or meta-surfaces in the nano-structure layer 110may be purely plasmonic, composed of metal nanoparticles, ormetallo-dielectric, composed of metals and dielectric nanoparticles, orpurely dielectric, composed of dielectric nanoparticles, typically highindex dielectrics. The photonic crystals and/or meta-surfaces in thenano-structure layer 110 may be fabricated using top-down or bottom-upfabrication methods and may utilize nanoparticle self-assembly toprovide advantages for manufacturing and scalability. Photonic crystalscan be fabricated for one, two, or three dimensions. One-dimensionalphotonic crystals can be made of layers deposited or stuck together.Two-dimensional ones can be made by photolithography, or by drillingholes in a suitable substrate. Fabrication methods for three-dimensionalones include drilling under different angles, stacking multiple 2Dlayers on top of each other, direct laser writing, or, for example,instigating self-assembly of spheres in a matrix and dissolving thespheres. The meta-atoms within photonic crystals and/or meta-surfaces inthe nano-structure layer 110 may be held together by differenttechniques including, but not limited to, molecular linkers, DNA, andthe like. Alternatively, they may be fabricated by top-down fabricationtechniques, such as nano-imprint lithography, nano-sphere lithography,or the like, and individual meta-atom released using lift-offtechniques. A nano-structure layer may be encapsulated by dielectricssuch as silicon dioxide or aluminum dioxide to prevent degradation ofmeta-atom properties over time.

FIG. 1I shows the phi averaged transmission 1000 versus angle plot for anano-structure layer, with TiOx nano-cylinders, the plot obtained at 450nm. As shown, the configuration of the nano-structure layer 110 enablesa unity or near unity transmission until a cutoff angle of approximately35 degrees and does not permit transmission after the cutoff angle.

FIG. 1J shows a transmission angular map for scattering by the TiOxnano-cylinder based nano-structure layer of FIG. 1I. The angular map isgenerated for such a nano-structure layer on sapphire substrate in abackground medium of air at 450 nm. The pitch of the hexagonal latticeused was 200 nm, the height of the rod was 250 nm and the radius was 56nm. It should be noted that similar results may be obtained for asilicon nano-rod at 840 nm with a height of 150 nm.

FIG. 1K shows a reflection angular map for scattering by the TiOxnano-cylinder based nano-structure layer of FIG. 1I. The angular map isgenerated for such a nano-structure layer on sapphire substrate in abackground medium of air at 450 nm. The pitch of the hexagonal latticeused was 200 nm, the height of the rod was 250 nm and the radius was 56nm. It should be noted that similar results may be obtained for asilicon nano-rod at 840 nm with a height of 150 nm.

FIG. 2A is a diagram of an LED device 200 in an example embodiment. TheLED device 200 may include one or more epitaxial layers 202, an activelayer 204, and a substrate 206. In other embodiments, an LED device mayinclude a wavelength converter layer and/or primary optics. As shown inFIG. 2A, the active layer 204 may be adjacent to the substrate 206 andemit light when excited. The epitaxial layers 202 may be proximal to theactive layer 204 and/or one or more intermediate layers may be betweenthe active layer 204 and epitaxial layers 202. The substrate 206 may beproximal to the active layer 204 and/or one or more intermediate layersmay be between the active layer 204 and substrate 206. The active layer204 emits light into the substrate 206.

FIG. 2B shows a cross-sectional view of a lighting system 220 includingan LED array 210 with pixels 201A, 201B, and 201C. The LED array 210includes pixels 201A, 201B, and 201C each including a respectivesubstrate 206B active layer 204B and an epitaxial layer 202B. Pixels201A, 201B, and 201C, in the LED array 210 may be formed using arraysegmentation, or alternatively using pick and place techniques and may,for example, emit light at different peak wavelengths such as red,green, and blue. The spaces 203 shown between one or more pixels 201A,201B, and 201C may include an air gap or may be filled by a materialsuch as a metal material which may be a contact (e.g., n-contact).According to some embodiments, secondary optics such as one or morelenses and/or one or more waveguides may be provided.

The LED device 200 or pixels 201A, 201B, and 201C may be singlewavelength emitters and may be powered individually or via as an array.The LED device 200 or pixels 201A, 201B, and 201C may be part of anillumination system that includes one or more electronics boards, powermodules, sensors, connectivity and control modules, LED attach regions,or the like. Pixels in an array may be powered based on differentchannel signals and their operation may be determined by amicrocontroller. The pixels 201A, 201B, and 201C may be manufactured inaccordance with the subject matter disclosed herein such that they mayhave respective nano-structure layers 210A, 210B, and 210C

FIG. 3 shows an example system 550 which includes an applicationplatform 560 and LED systems 552 and 556. The LED system 552 produceslight beams 561 shown between arrows 561 a and 561 b. The LED system 556may produce light beams 562 between arrows 562 a and 562 b. As anexample embodiment, the LED system 552 and 556 may be part of anautomobile and may emit infrared (IR) light communication beams suchthat an oncoming vehicle in the path of the light beams 561 and/or 562is able to receive communication from the automobile. In exampleembodiments, the system 550 may be a mobile phone of a camera flashsystem, indoor residential or commercial lighting, outdoor light such asstreet lighting, an automobile, a medical device, AR/VR devices, androbotic devices.

The application platform 560 may provide power to the LED systems 552and/or 556 via a power bus via line 565 or other applicable input, asdiscussed herein. Further, application platform 560 may provide inputsignals via line 565 for the operation of the LED system 552 and LEDsystem 556, which input may be based on a user input/preference, asensed reading, a pre-programmed or autonomously determined output, orthe like. One or more sensors may be internal or external to the housingof the application platform 560.

In various embodiments, application platform 560 sensors and/or LEDsystem 552 and/or 556 sensors may collect data such as visual data(e.g., LIDAR data, IR data, data collected via a camera, etc.), audiodata, distance based data, movement data, environmental data, or thelike or a combination thereof. The data may be collected based onemitting an optical signal by, for example, LED system 552 and/or 556,such as an IR signal and collecting data based on the emitted opticalsignal. The data may be collected by a different component than thecomponent that emits the optical signal for the data collection.Continuing the example, sensing equipment may be located on anautomobile and may emit a beam using a vertical-cavity surface-emittinglaser (VCSEL). The one or more sensors may sense a response to theemitted beam or any other applicable input.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with orwithout the other features and elements. In addition, the methodsdescribed herein may be implemented in a computer program, software, orfirmware incorporated in a computer-readable medium for execution by acomputer or processor. Examples of computer-readable media includeelectronic signals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs).

What is claimed is:
 1. A light emitting device comprising: asemiconductor diode structure; a transparent substrate transparent tolight emitted by the semiconductor diode structure and comprising a topsurface, an oppositely positioned bottom surface, and side surfacesconnecting the top and bottom surfaces, the bottom surface disposed onor adjacent the semiconductor diode structure; and a nanostructuredlayer disposed on or adjacent the top surface of the transparentsubstrate and comprising a plurality of nano-antennas disposed in adielectric medium in a periodic or a-periodic arrangement such thatlight emitted by the semiconductor diode structure into the transparentsubstrate and incident on the nanostructured layer at an angle ofincidence less than a cut-off angle is transmitted through thenanostructured layer and light emitted by the semiconductor diodestructure into the transparent substrate and incident on thenanostructured layer at an angle of incidence greater than or equal tothe cut-off angle is reflected back into the transparent substrate. 2.The light emitting device of claim 1, wherein the cut-off angle is lessthan or equal to 10 degrees.
 3. The light emitting device of claim 1,wherein the cut-off angle is less than or equal to 20 degrees.
 4. Thelight emitting device of claim 1, wherein light emitted by thesemiconductor diode structure into the transparent substrate andincident on the nanostructured layer at an angle of incidence less thanthe cut-off angle is transmitted through the nanostructured layer withina cone angle of +/−60 degrees.
 5. The light emitting device of claim 4,wherein light emitted by the semiconductor diode structure into thetransparent substrate and incident on the nanostructured layer at anangle of incidence less than the cut-off angle is transmitted throughthe nanostructured layer within a cone angle of +/−45 degrees.
 6. Thelight emitting device of claim 5, wherein light emitted by thesemiconductor diode structure into the transparent substrate andincident on the nanostructured layer at an angle of incidence less thanthe cut-off angle is transmitted through the nanostructured layer withina cone angle of +/−5 degrees.
 7. The light emitting device of claim 1,wherein the arrangement of nano-antennas is periodic.
 8. The lightemitting device of claim 1, wherein the arrangement of nano-antennas isa-periodic.
 9. The light emitting device of claim 1, wherein eachnano-antenna has a largest dimension less than or equal to a wavelengthof light emitted by the semiconductor diode structure.
 10. The lightemitting device of claim 1, wherein at least one nano-antenna is asingle light scattering object.
 11. The light emitting device of claim1, wherein at least one nano-antenna comprises two or more lightscattering objects.
 12. The light emitting device of claim 1, whereinthe plurality of nano-antennas comprises a plurality of nano-cones. 13.The light emitting device of claim 12, wherein the nano-cones eachcomprise a coaxial dimmer or a vertical dimmer.
 14. A light emittingdevice comprising: a semiconductor diode structure; a transparentsubstrate transparent to light emitted by the semiconductor diodestructure and comprising a top surface, an oppositely positioned bottomsurface, and side surfaces connecting the top and bottom surfaces, thebottom surface disposed on or adjacent the semiconductor diodestructure; and a nanostructured layer disposed on or adjacent the topsurface of the transparent substrate and comprising a plurality ofnano-antennas arranged in a hexagonal or rectangular lattice such thatlight emitted by the semiconductor diode structure into the transparentsubstrate and incident on the nanostructured layer at an angle ofincidence less than a cut-off angle is transmitted through thenanostructured layer and light emitted by the semiconductor diodestructure into the transparent substrate and incident on thenanostructured layer at an angle of incidence greater than or equal tothe cut-off angle is reflected back into the transparent substrate. 15.The light emitting device of claim 14, wherein the plurality ofnano-antennas is arranged in a hexagonal lattice.
 16. The light emittingdevice of claim 14, wherein the plurality of nano-antennas is arrangedin a rectangular lattice.
 17. A light emitting device comprising: asemiconductor diode structure; a transparent substrate transparent tolight emitted by the semiconductor diode structure and comprising a topsurface, an oppositely positioned bottom surface, and side surfacesconnecting the top and bottom surfaces, the bottom surface disposed onor adjacent the semiconductor diode structure; and a nanostructuredlayer disposed on or adjacent the top surface of the transparentsubstrate and comprising a plurality of nano-antennas arranged with aspatial gradient of phase such that light emitted by the semiconductordiode structure into the transparent substrate and incident on thenanostructured layer at an angle of incidence less than a cut-off angleis transmitted through the nanostructured layer and light emitted by thesemiconductor diode structure into the transparent substrate andincident on the nanostructured layer at an angle of incidence greaterthan or equal to the cut-off angle is reflected back into thetransparent substrate.
 18. The light emitting device of claim 17,wherein the plurality of nano-antennas comprises a plurality ofnano-cones.
 19. The light emitting device of claim 18, wherein thenano-cones each comprise a vertical dimer.
 20. The light emitting deviceof claim 18, wherein the nano-cones each comprise a coaxial dimer.